Polyurethane-ureas based on cis-trans-1,4-diaminocyclohexane

ABSTRACT

Light stable polyurethane coatings with a considerably increased softening range and melting points coupled with improved resistance to perchlorethylene is obtained by using a chain extender comprising at least 80 mol % 1,4-diamino cyclohexane with a cis/transisomer ratio of from 10/90 to 60/40 .Iadd.and by using aliphatic or cycloaliphatic diisocyanates wherein such diisocyanates consist of at least 75 mol percent of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane.Iaddend..

This invention relates to a process for the production of stablesolutions of aliphatic, substantially linear segmented polyurethane-ureaelastomers in weakly polar solvents of relatively high volatility, andto the production of light-stable films and coatings with high softeningranges from such solutions.

It is known that substantially linear polyurethanes can be obtained fromsolutions of relatively high molecular weight polyhydroxy compounds suchas polyesters, aliphatic or cycloaliphatic diisocyanates such ashexamethylene diisocyanate, dicyclohexyl methane diisocyanate or1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane, andchain-extending agents such as ethylene diamine,1-amino-3-amino-methyl-3,5,5-trimethyl cyclohexane or 4,4'-dicyclohexylmethane diamine. Highly polar amides such as dimethyl formamide can beused as solvents. Polyurethanes based on 1-isocyanoto-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane and/or1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane, in particular, arealso soluble in weakly polar solvents such as toluene/isopropanol whichsimplifies to a very considerable extent the processing of polyurethanesolutions such as these into coatings, because high-boiling,physiologically unacceptable solvents such as dimethylformamide can beavoided.

On account of their synthesis from (cyclo) aliphatic diisocyanates and(cyclo) aliphatic diamine components, polyurethane-ureas of this kind donot discolor on exposure to light and are considerably more stable thancomparable polyurethanes based on aromatic diisocyanates such as, forexample, diphenylmethane-4,4'-diisocyanate. Accordingly, they are usedwith advantage in the production of flexible textile coatings or assurface layers on coatings. Unfortunately, their favorable solubilityand light-stability properties are offset by their typically unfavorableproperty of a relatively low softening range and a relatively lowmelting point. Thus, polyurethane-ureas of this kind begin to soften attemperatures far below 200° C and, in some cases, even at temperaturesbelow 150° C, while their melting point (Kofler bench) is generallybetween 180 and 210° C, even in the case of relatively "hard"polyurethanes (high NCO-content in the prepolymer, for example 5.5% byweight). In the case of coatings, the low softening range impairsfastness to rubbing under heat and resistance to hot ironing or behaviorin heated presses (for example, in the case of artificial leather). Inaddition, coatings of this kind frequently show very high swellabilityin solvents of the kind used in dry cleaning, such as perchlorethylene.

It has now surprisingly been found that light-stable polyurethanecoatings with a considerably increased softening range and meltingpoints, coupled with improved resistance to perchlorethylene, can beobtained by using 1,4-diamino cyclohexane in certain stereoisomericcis/trans-mixtures as chain extender which also results in thepolyurethane-ureas formed having outstanding resistance to solvents.

The invention therefore relates to a process for the production ofstable, light-resistant solutions of polyurethane ureas from prepolymerswith terminal isocyanate groups and diamines in weakly polar solvents,distinguished by the fact that prepolymers of

a. substantially linear polyhydroxyl compounds with molecular weights offrom about 500 to 5000,

b. optionally low molecular weight dihydroxy compounds,

c. and aliphatic or cycloaliphatic diisocyanates, the molar ratio ofhydroxyl groups to isocyanate groups being between about 1 : 1.5 and 1 :5,

are reacted with diamines as chain extenders in a solvent or mixture ofsolvents of aromatic which may be chlorinated and/or chlorinatedaliphatic hydrocarbons and primary, secondary and/or tertiary aliphaticand/or cycloaliphatic alcohols, at least 80 mol % of the chain extenderbeing 1,4-diamino cyclohexane with a cis/trans-isomer ratio of from 10 :90 to 60 : 40.

The polymers prepared in accordance with the invention generally melt attemperatures in the range of from 250 to 270° C and begin to soften attemperatures of from about 215 to 240° C. The thermal properties areaccordingly improved by some 50 to 60° C by using the chain extendersaccording to the invention. In addition, the polyurethanes according tothe invention are also extremely fast to light and can be prepared in ahighly hydrolysis-stable composition by using dihydroxy polycarbonatesbased on hexane diol as the relatively high molecular weightpolyhydroxyl compounds. It is possible, by the incorporation of lowmolecular weight diols containing tertiary amine groups, to obtain afurther improvement in light-stability beyond the already existingstability level.

Although the use of pure trans-1,4-diamino cyclohexane as chain extenderalso leads to products of very high melting point, it does involve thedisadvantage that the polyurethanes synthesized in this way do notremain stably dissolved in many of the solvent mixtures according to theinvention and rapidly change from their solutions into a paste-like,gelled form in which they are no longer suitable for processing intocoatings. With pure cis-1,4-diamino cyclohexane the melting point of thepolyurethane coatings falls again and approaches the behavior of knownpolyurethanes based on conventional diamine extenders as describedabove. A lower softening range is also found with 1,3-diaminocyclohexane.

By using a certain cis/trans-mixture of the stereoisomeric 1,4-diaminocyclohexanes in accordance with the invention, it is possible to obtainboth a considerably improved softening range and melting range of thepolyurethanes and also an adequate level of solubility of thesepolyurethanes in the moderately polar solvent mixtures of comparativelyhigh volatility that are preferably used.

At the same time, a distinct improvement in light stability is obtained,by comparison with the products obtainable with conventional chainextending agents.

The cis-enriched diamino cyclohexanes are liquid and can readily beseparated from the isomer mixture; the trans-compound of the 1,4-diaminocyclohexane is crystalline and can be readily recrystallized, forexample from petroleum ether, and obtained in pure form. Thecis/trans-ratio can be determined by nuclear resonance spectroscopy (220mc/s apparatus) at 2.836 ppm and 2.597 ppm.

The preferred cis/trans-ratios of the 1,4-diamino cyclohexane are from50 : 50 to 15 : 85, the most favorable range being from about 40 : 60 to20 : 80.

The substantially linear polyurethane ureas are prepared by methodsknown per se. Substantially linear polyhydroxyl compounds such asdihydroxy polyesters, polycarbonates and polyacetones with molecularweights of from about 500 to 5000 (preferably from 800 to 3000) andmelting points below 60° (preferably below 45° C) are reacted with thealiphatic and/or cycloaliphatic diisocyanates in an NCO : OH molar ratioof from about 1.5 : 1 to 5 : 1, preferably from 2 : 1 to 3 : 1, to formthe NCO prepolymer. (If the molar ratio is greater than 2 : 1, thereacted mixture contains fractions of the monomeric diisocyanate inaddition to the NCO prepolymer. In the following, the term "prepolymer"is also intended to cover mixtures of this kind).

Examples of polyesters suitable for the process according to theinvention include adipic acid-ethylene glycol, -1,6-hexane diol,-2,2-dimethyl propane diol, -1,4-butane diol or -1,2-propane diolpolyester or mixtures of these components. The adipic acid in thepolyesters may also to some extent be replaced, for example, by phthalicacid or isophthalic acid. Polycaprolactone ester types which contain thehydroxy caproic acid unit as a structural component, are particularlysuitable because of their resistance to hydrolysis. Dihydroxypolycarbonates based on 1,6-hexane diol or mixed polycarbonates intowhich adipic acid, for example, is incorporated in small quantitiesinstead of carbonic acid, for example in quantities of about 20 mol %,are even more suitable because of their outstanding resistance tohydrolysis. Mixtures of the aforementioned compounds can also be used.

In addition to the relatively high molecular weight polyhydroxycompounds, low molecular weight diols with molecular weights of from 62to about 400, for example ethylene glycol, 1,4-butane diol, 2,3-butanediol; 2,2-dimethyl-1,3-propane diol or N-stearyl-N',N'-bisoxethyl urea,can also be used in relatively small quantities (about 0.05 to 1 mol perkg of elastomer) in the preparation of the prepolymer. Diols containingtertiary amino groups, for example N,N-bis(β-hydroxy ethyl)-methylamine,N,N-bis(β-hydroxy ethyl)-isopropyl amine, N,N-bis(β-hydroxypropyl)-tert.-amylamine and bis-(3-aminopropyl)-piperazine, areparticularly preferred because, in this way, a considerable furtherimprovement in stability against loss of strength under the effect oflight is obtained in the already light-stable non-discoloringpolyurethanes. Other diol compounds containing tertiary amino groupssuitable for use in the process according to the invention are describedin German Offenlegungsschrifts Nos. 1,495,830 and 2,058,502.

The preferred isocyanate component is 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane, which may be mixed with smallerquantities (of up to about 25 mol %) of other aliphatic orcycloaliphatic diisocyanates, for examplehexamethylene-1,6-diisocyanate; 2,2,4-trimethyl hexane-1,6-diisocyanate;4,8-dioxa-6,6-dimethyl undecane-1,11-diisocyanate; lysine-C₁ -C₆ -alkylester diisocyanates; 1,4-dicyclohexane diisocyanate and, in particular,4,4'-dicyclohexyl methane diisocyanate or3,3'-dimethyl-4,4'-dicyclohexyl methane diisocyanate (preferably in theform of the cis/cis- or cis/trans-enriched stereoisiomer mixtures).

1,4-diamino cyclohexane with cis/trans-isomer ratio according to theinvention can be used on its own as a chain extender, although it isalso possible to use other, preferably amino functional compounds knownper se, although their content should preferably not amount to any morethan 20 mol % of the chain extenders, so that the melting point of thepolyurethanes is not excessively reduced. Other chain extenders arepreferably added in quantities of up to about 12 mol %, for exampleethylene diamine, 1,2-propylene diamine, hexamethylene diamine,N-methyl-bis (3-amino propyl)-amine, bis-N,N'-(3-aminopropyl)-piperazine, 1,3-cyclohexane diamine, 4,4'-dicyclohexyl methanediamine, 3,3'-dimethyl-4,4'-diamino dicyclohexyl methane and1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane. Preferredco-extenders include ethylene diamine, dicyclohexyl methane diamine and1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane.

It is also usually possible to use small quantities of monoamines oramino alcohols for chain termination of the polyaddition reaction andsmall quantities of triamines to increase viscosity.

In the process according to the invention, the diamines are reacted withthe NCO-prepolymers in preferably equivalent or slightly excessquantities (for example in NH₂ : NCO molar ratios of 1 : 1 to 1.15 : 1).Due to the avoidance of an excess of NCO, solutions of this kind arehighly stable on storage. The free amino groups can also be reacted withdiisocyanates and polyisocyanates in, at most, equivalent quantities(accompanied by an increase in viscosity) or with monoisocyanates (toremove terminal amino groups).

The polyurethanes which can be obtained by the process according to theinvention contain typical ("hard/segments" (of diisocyanate anddiamines) with the structure: ##STR1## in which the groups D arepredominantly radicals of the formula ##STR2## and x is an integer offrom 1 to 5. In addition, D can also be a radical of a (cyclo) aliphaticdiisocyanate, for example the hexamethylene radical or thedicyclohexylmethane radical ##STR3## Structures containing the radical##STR4## either exclusively or in a proportion of at least 75%, arepreferred. If the proportion of other (cyclo) aliphatic diisocyanates isincreased appreciably further (for example 50% of dicyclohexyl methane),the polyurethane ureas become insoluble in the solvents used in theprocess according to to the invention. The 1,4-diamino cyclohexaneradical ##STR5## is present in cis/trans stereoisomeric proportions offrom 10/90 to 60/40, preferably from 15/85 to 50/50. These radicals canbe replaced by other (cyclo)-aliphatic diamines as chain extenders inquantities of up to about 20 mol %, preferably in quantities of up to 12mol %.

The hard segments are generally attached through urethane groups to theso-called "soft-segments" which preferably consist of a lineardihydroxy-polyester, -polycaprolactone or -polycarbonate. In principle,a soft segment may also be a polyether radical, although the lightstability of polyurethanes such as there is low in the absence ofspecific stabilization.

In addition to the hard segment structures, the incorporation of lowmolecular weight dihydroxy compounds into the prepolymer also gives riseto the formation of structural segments such as

    --CO.NH-D-NH.CO.O-G-O.CO.NH-D-NH.CO--

which are attached to the relatively high molecular weight dihydroxycompounds through urethane groups and/or to the hard segments throughurea groups. G is the radical of the low molecular weight dihydroxycompound, for example an alkylene or cycloalkylene radical with up to 13carbon atoms and, preferably, an N-alkyl-(alkylene)₂ -radical in whichthe primary, secondary or tertiary alkyl group contains from 1 to 12carbon atoms and the alkylene groups contain from 4 to 10 carbon atoms.

Solvent mixtures of aromatic or aliphatic hydrocarbons which may bechlorinated with primary, secondary, and/or tertiary aliphatic and/orcycloaliphatic alcohols, are particularly suitable for use as solventsfor the substantially linear, aliphatic polyurethane ureas with theaforementioned structures and for the process according to theinvention. The solutions have solids contents of from about 5 to 40% byweight, preferably from 15 to 35% by weight. Examples of thehydrocarbons used in the process according to the invention includetoluene, xylene, ethyl benzene, mesitylene, chlorotoluenes andhydrocarbon cuts of petroleum or synthesis fractions predominantlycontaining aromatic hydrocarbons (for example Esso's Solvesso-100 ofb.p. 156-178° C., flashpoint 45° C). Compounds such as trichloroethyleneor perchlorethylene are used as the chlorinated aliphatic hydrocarbonswhile preferred alcohols include C₂ -C₈ alcohols such as ethanol,propanol, isopropanol, butanol, isobutanol, primary, secondary, ortertiary amyl alcohols, primary, secondary or tertiary hexyl alcohols,tert.-butanol or tert.-octyl alcohol, and also diacetone alcohol.Mixtures of toluene or xylene with isopropanol, isobutanol ortert.-butanol are particularly effective solvents. The solvent mixtures(in hydrocarbon : alcohol quantitative ratios of 1 : 10 to 10 : 1,preferably from 1 : 3 to 3 : 1) have better dissolving properties thanthe individual components. Relatively high boiling solvent mixtures suchas Solvesso/ethylene glycol monomethyl ether or Solvesso/ethylene glycolmonoethyl ether have the advantage of giving the solution a higherflashpoint although, on the other hand, they are more difficult toremove again than the readily volatile solvents during the furtherprocessing of the polymer solutions.

Other solvents may be added as diluents to the solutions beforeprocessing, for example before spraying of the solutions, in order toobtain the low viscosity required. On the other hand, any requiredfilm-forming rate can be adjusted by additions of high-boiling solvents.Examples of such solvents include methylene chloride, tetrahydrofuran,dioxan, ethyl acetate, methyl ethyl ketone, amyl acetate or, ashigh-boiling solvents, ethylene glycol monomethyl ether acetate or evendimethyl formamide in small quantities.

Such additives as stabilizers, anti-agers, hydrolysis stabilizers,UV-absorbers, soluble dyes, pigments of organic or inorganic structure,fillers, carbon black or white pigments can be added in the usual formand quantities of the polyurethane solutions as known per se formodification purposes. Whiteners or other soluble high molecular weightsubstances, such as nitrocellulose, cellulose esters and ethers andother derivatives, also soluble polymers or polycondensates, can also beadded.

Application of the polyurethane urea solution mixtures for layerformation to substrates or intermediate supports is carried out by anyprocess known per se, for example by casting, doctor-coating, spreadcoating, brush-coating, spray-coating or printing. Textile coatings on,for example, webs, woven fabrics or knitted fabrics can be applied inrelatively thick layers in the case of relatively soft polyurethanesettings (softness controlled by the NCO-content of the prepolymer usedfor preparation; for example 2.5 to 4.5% by weight of NCO) in anyconstructions and aftertreatment stages (for example roughenedsurfaces). The solution mixtures can also be applied to intermediatesupports, for example release papers, steel bands or siliconizedfabrics, in which case the films formed can be further processed bybonding or by the reversal process.

In one preferred procedure, roughened cotton fabric weighingapproximately 220 to 240 g/cm² is coated with the polyurethane solutionby the reversal process on a coating machine by means of doctor rolls.To this end, a surface layer is applied with the solution to the releasepaper and dried in a first operation through the drying ducts of thecoating machine at temperatures rising from 80 to 120° C. The coating isapplied in a quantity of from about 40 to 50 g/cm² of solid substance.In a second operation, the elastomer solutions are diluted withapproximately 5 to 10% of dimethyl formamide or cyclohexanone and areapplied as an adhesive coat to the dry surface layer, the fabric islaminated on and the web dried again in the drying duct. The releasepaper and the laminated fabric are separately wound up after leaving thedrying duct. The total application of polyurethane to the fabric amountsto between about 60 and 90 g/cm². Approximately 10 to 20% of pigmentscan be incorporated in the solutions in order to provide them with anyrequired color.

Harder polyurethane settings (NCO-contents of from about 4 to 7% byweight in the prepolymer) are preferably applied as surface coats or asfinished to textile coatings, leather or artificial leather, for exampleby doctor-coating, spray-coating or printing, and the solvent is removedby brief heating, for example by heating for 3 minutes at 170° C.

The invention is further illustrated but is not intended to be limitedby the following examples in which all parts and percentages are byweight unless otherwise specified.

EXAMPLE 1 NCO-prepolymer formation

1200 parts of a 1,6-hexane diol polycarbonate with an OH number of 58.25(molecular weight 1925) are stirred with 25.7 parts of N,N-bis(β-hydroxypropyl)-methyl amine, a solution of 405.8 parts of1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane in 408parts of Solvesso-100 (aromatic solvent cut with a flashpoint above 45°C, an Esso product) is added at 65° C and the 80% solution issubsequently heated for 2 hours to 95° C for prepolymer formation. Theprepolymer has an NCO-content of 5.28% (calculated on solid substance).

a. Chain extension with 1,4-diamino cyclohexane (36% cis/64%trans-ratios)

9.25 parts of 1,4-diamino cyclohexane are dissolved in 371 parts of anethylene glycol monoethyl ether/Solvesso-100 mixture (1 : 1 parts byweight) and 155.5 parts of prepolymer solution introduced in the form ofa thin stream with vigorous stirring (102 equivalents of NH₂ to 100equivalents of NCO). The homogeneous highly viscous 25% solution formedhas a solution viscosity of 1050 poises/20° C. The properties of filmscast from this solution (doctor-coating on to glass plates, followed byevaporation of the solvent at about 70 to 100° C) are shown in Table 1.

The solution shows outstanding levelling behavior, even after standingfor several weeks.

A finish prepared from the solution on sheets of artificial leather issurprisingly resistant to aqueous-alcohol mixtures, in contrast topolyurethanes which have been chain extended for example with ethylenediamine or 1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane (seecomparison tests). However, the substance is readily soluble in thesolvent mixture used for production and in mixtures of toluene andisopropanol.

In order to test the properties of the finish, 100 parts of the 25%PUR-solution (dissolved in a mixture of Solvesso-100 and ethylene glycolin a ratio of 1 : 1) are diluted with 50 parts of a solvent mixture of50% of ethylene glycol, 25% of toluene and 25% of isopropanol andapplied with a doctor knife in a layer thickness of 12 μ to a knittedfabric which has been coated with polyurethane by the reversal process.After drying for 1 minute at 140° C and cooling, the finished materialis dry, has a very fine gloss coupled with a pleasant feel and showsfavorable fastness to rubbing and flexing:

300 rub-strokes under a load of 1 kp with a VESLIC apparatus (accordingto Schweize Farbechtheitsprufungsblatt C 4500);

over 100,000 flexings according to DIN 53 340.

The finish is resistant to rubbing with 50% alcohol, it shows verymoderate resistance to 98% alcohol. Its fastness to light, as measuredon the 8-stage international blue scale, is greater than 7. Afterstorage for 4 weeks at 70° C/98% relative humidity, a film prepared fromthe polyurethane solution still has 94% of its original ultimate tensilestrength which is outstanding for polyester polyurethanes. 100 parts ofthe lacquer of Example 1a, but prepared in a mixture of tert.-butanoland xylene (1 : 1), are dissolved in 300 parts of a mixture of equalparts of ethyl glycol, dimethyl formamide and toluene and colored with astandard light-brown nitrocellulose pigment (Bayer's Egaloncaramel).This solution is sprayed on to the embossed surface of an artificialleather (5 to 6 g of dry substance per m²). The artificial leatherconsists of a latex-bonded polyamide fiber web with a surface layer ofcoagulated polyurethane (approximately 0.3 mm thick). After spraying anddrying of the finish, the unpleasant rubber-like feel has completelydisappeared. The surface shows a fine gloss, coupled with highresistance to flexing, scratching and rubbing. The resistance of thefinish to aliphatic hydrocarbons is extremely good and is resistance toconcentrated alcohol is moderate.

b. Comparison test

Chain extension with trans-1,4-diaminocyclohexane

The trans-1,4-diamino cyclohexane is obtained by treating the semi-solidcis/trans-mixture of (a) with petroleum ether, filtering off the solidfraction under suction and recrystallizing the solid isomer from petrolwith a melting point of 65 to 67° C and a trans-isomer content of 97%.

9.25 parts of the trans-isomer of 1,4-diamino cyclohexane are reactedwith 155.5 parts of the prepolymer solution of 1(a) (102 equivalents ofNH₂ to 100 equivalents of NCO). A homogeneous, highly viscous 25%solution is obtained, becoming steadily more viscous in a matter ofminutes so that it is diluted with 132 parts of a Solvesso/ethyleneglycol mixture to a solids content of 20%. The solution then has aviscosity of around 1500 poises and changes into a totally gelled form(crumbly without any flow properties) over another 30 minutes at roomtemperature. A coating is applied from the paste, the solvent evaporatedoff and the v_(i) -value measured in hexamethyl phosphoramide. The v_(i)-value of 0.85 corresponds to a conventional high-polymeric linearpolyurethane elastomer. Accordingly, gelling is by no means attributableto crosslinking, but merely to an increase in viscosity. The substancehas an extremely high softening point and melting point (see Table 1),but in this composition is neither solvatable nor soluble in theaforementioned solvents, but only in highly polar solvents such asdimethyl formamide.

c. Comparison test

Chain extension with cis-enriched 1,4-diamino cyclohexane (75% cis/25%trans)

The sample is obtained by decanting off the liquid fractions from thestereoisomer mixture of diamino cyclyhexane which is semi-solid at roomtemperature and, according to NMR-analyzing, contains 74.8% of cis- and25.2% of trans-isomers.

9.25 parts of the cis-enriched 1,4-diamino cyclohexane are reacted with155.5 parts of the prepolymer solution of 1(a) to form a homogeneous,highly viscous 25% solution and diluted to a solids content of 20.4%.After 1 day, this solution has lost its homogeneity and flow propertiesand, after 2 days, has changed into a paste-like form. Some of thesolution was diluted to 15% immediately after preparation and cast intofilms (see Table 1). The softening point is distinctly lower than intest 1a.

d. Chain extension with a mixture of cis-enriched and trans-1,4-diaminocyclohexane

Equal parts of the trans-isomer used in 1(b) (97% trans/3% cis) and thecis-mixture used in 1(c) (74.8% cis/25.2% trans) are used for chainextension, giving a mixture with a trans-isomer content of 61.6% and acis-isomer content of 38.4%.

9.25 parts of the (38.4% cis/61.6% trans)-1,4-diamino cyclohexane arereacted as in 1(a) with 155.5 parts of prepolymer solution, resulting inthe formation of a homogeneous, highly viscous and stable elastomersolution. Following dilution of part of the solution, films are preparedand their properties determined (see Table 1). The technical propertiescorrespond to those of Example 1a.

e. Comparison test

Chain extension with ethylene diamine

3.25 parts of ethylene diamine in 230 parts of Solvesso/ethyl glycol (1: 1) are mixed with stirring with 107.5 parts of the NCO-prepolymersolution (equivalent quantity), resulting in the formation of a clearhomogeneous solution with a viscosity of 286 poises at 20° C (c =26.6%). The solution remains stable over several weeks. Films cast fromthe solution show the properties set out in Table 1.

The low melting and softening points of these elastomers are remarkable.

On exposure to light, the films are far less stable to dehydration thanfilms prepared according to Example 1a although neither of the two filmsdiscolors under Xenotest or Fadeometer test conditions.

The coatings soften very considerably when treated with alcohol orwater/alcohol (1 : 1) and are seriously damaged by even gentle rubbing.This behavior is also shown by coatings of polyurethanes prepared with1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane instead of ethylenediamine.

                                      Table 1                                     __________________________________________________________________________    Solution and film properties of polyurethane ureas according to Example            1,4-diaminocyclo                                                                         solution                                                                             Solution                                                    hexane     viscosity                                                                            concentration                                          Example                                                                            cis/trans content (%)                                                                    poises/20° C                                                                  (% by weight)                                                                            η i-value                               __________________________________________________________________________    1 a) 36/64%     1050   25         0.76                                        1 b)  3/97%     1500   20         0.85                                             (comparison test) (very quickly gelled)                                  1 c) 75/25      2000   20.4       0.88                                             (comparison test)                                                        1 d) 38.4/61.6  2500   20.5       0.96                                        1 e) ethylene diamine                                                                         286    26.2       --                                               (comparison test)                                                        Ultimate               Heat distortion                                                                          Melting behavior                            tensile         Breaking                                                                             temperature                                                                              Kofler bench                                     strength   elongation                                                                           HDT:(cf DOS                                                                              softening                                                                           melting point                         Example                                                                            g/dtex     (%)    1770591)   ° C                                                                          ° C                                                                           Remarks                        __________________________________________________________________________    1 a) 0.74       447    143.5      >235° C                                                                      >260° C                                                                       Solution stable                                                        almost liquid                         1 b) cannot be  no film                                                                              --         approx.                                                                             (>260° C)                                                                     solution unstable.                  measured                     260° C                                                                              turning immediately                                                           into a paste                   1 c) 0.84       471    124        >215-220                                                                            >239   solution unstable.                                                            turning into a paste                                                          after standing for                                                            1 day                          1 d) 0.80       481    154        >230-245                                                                            >260 liquid                                                                          solution stable                1 e) 0.83       442    103         175-193                                                                            >205 liquid                                                                          film damaged when                                                             rubbed with                    __________________________________________________________________________                                                   ethanol                    

EXAMPLE 2

A prepolymer solution is prepared in accordance with Example 1, the onlydifference being that toluene is used as the solvent, instead ofSolvesso-100. The prepolymer solution obtained has an NCO-content of5.32%, based on solids. The chain-extending reactions are carried out intoluene/isopropanol (ratio by weight 1 : 1).

a. Chain extension with 1,4-diamino cyclohexane (82.7% trans/17.3% cis)

69.3 parts of 1,4-diamino cyclohexane (17.3% cis/82.7% trans) aredissolved in 2411 parts of toluene/isopropanol (1 : 1) and 1200 g of theabove NCO-prepolymer solution (the equivalent quantity) stirred in. Thehomogeneous solution has a viscosity of 680 poises. After an observationperiod of 1 month, the solution was still free-flowing. The filmproperties are shown in Table 2. The technical properties as a finishcorrespond to the values given in Example 1a. If toluene is replaced bychlorobenzene, homogeneous storage-stable elastomer solutions are alsoobtained, from which finishes with the properties and characteristicsgiven in Example 1a can be prepared.

b. Co-extension with 1,4-diamino cyclohexane/ethylene diamine (90 : 10)

5.18 parts of the 1,4-diamino cyclohexane used in 2a and 0.31 parts of98% ethylene diamine are dissolved in 235 parts of toluene/isopropanol(1 : 1) and stirred with a substantially equivalent quantity of theNCO-prepolymer to form a homogeneous solution with a viscosity of 270poises at 20° C and a solids content of 25%. The solution remains stableover the observation period of 1 month; the properties of the films areset out in Table 2. The high melting point of 2a remains substantiallyunaltered.

c. Co-extension with 1,4-diamino cyclohexane/ethylene diamine (80 : 20)

In the event of similar extension with 20 mol % of ethylene diamine asco-extender (4.62 parts of diamino cyclohexane/0.62 parts of ethylenediamine), a homogeneous storage-stable solution with a viscosity of 270poises/20° C and a solids content of 25% is also obtained.

d. Co-extension of 1,4-diamino cyclohexane with1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane (90/10)

If 10 % of 1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane are usedinstead of the ethylene diamine (5.18 parts of 1,4-diamino cyclohexaneaccording to 2a/0.86 parts of 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane), with the procedure otherwise the same as in Example 2b, astorage-stable homogeneous elastomer solution with a viscosity of 380poises/20° C, c = 25%, is obtained. The properties of the films aregiven in Table 2.

e. Co-extension of 1,4-diamino cyclohexane with 1,3-diamino cyclohexane(90/10)

5.18 parts of 1,4-diamino cyclohexane and 0.58 parts of 1,3-diaminocyclyhexane are similarly reacted to form a homogeneous, storage-stablesolution (viscosity = 220 poises at 20° C). The properties of the filmsare given in Table 2.

                                      Table 2                                     __________________________________________________________________________    Solution and film properties of the polyurethane ureas according to           Example 2                                                                          1,4-diamino cycle                                                                        solution                                                           hexane     viscosity                                                          cis/trans content                                                                        poises/                                                                             solution                                                Example                                                                            17.3/82.7% 20° C                                                                        concentration                                                                          η i-value                                  __________________________________________________________________________    2 a) 100%       680   28       0.85                                           2 b) 90% 1,4-diamino                                                                          270   25       --                                                  cyclohexane                                                                   10% ethylene                                                                  diamine                                                                  2 c) 80% 1,4-diamino                                                                          270   25       0.84                                                cyclohexane                                                                   20% ethylene                                                                  diamine                                                                  2 d) 90% 1,4-diamino                                                                          380   25       0.85                                                cyclohexane                                                                   10% 1-amino-3-                                                                aminomethyl-3,5,5-                                                            trimethyl cyclohexane                                                    2 e) 90% 1,4-diamino                                                                          220   25       0.82                                                cyclohexane                                                                   10% 1,3-diamino                                                               cyclohexane                                                              Ultimate              HDT determined                                                                         melting behavior                               tensile         Breaking                                                                            in accordance                                                                          Kofler bench                                        strength   elongation                                                                          with DOS 1770591                                                                             melting point                            Example                                                                            g/dtex     (%)   (° C)                                                                           softening                                                                           (liquid) ° C                      __________________________________________________________________________    2 a) 0.76       434   157      >240  >265                                     2 b) 0.73       425   147      >235  >255                                     2 c) 0.76       400   144      >225  >250                                     2 d) 0.80       443   153      >(220-)240                                                                          >260                                     2 e) 0.79       407   152      >(215- )240                                                                         >264                                     __________________________________________________________________________

EXAMPLE 3

600 parts of the hexane diol polycarbonate of Example 1 are heated forsome 220 minutes to 97° C with 138.5 parts of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane and 185.5 parts of Solvesso-100,resulting in the formation of a prepolymer solution with an NCO-contentof 3.58% (based on the solid substance).

a. Chain extension with 1,4-diamino cyclohexane (17.3% cis/82.7% trans)

4.2 parts of diamino cyclohexane are introduced into 233 parts ofSolvesso/ethylene glycol (1 : 1) and 107.5 parts of the prepolymersolution introduced with stirring. A homogeneous, storage-stablesolution with a viscosity of 266 poises/20° C is obtained.

Films of this solution show a melting point of 260° C, softeningbeforehand at temperatures upwards of about 225 to 235° C. Softening issomewhat more pronounced than in Example 1 because the urethane has a"softer" structure (less NCO, i.e. less hard segment). v_(i) -value =0.70) see (Table 3).

Chain extension can also be carried out in toluene/isopropanol andxylene/tert.-butanol mixtures (3 : 1 to 1 : 3), stable solutions againbeing obtained.

Comparison test

Chain extension with ethylene diamine and with1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane

Elastomer solutions are prepared and cast into films in the same way asin test 3a, but with 2.25 parts of 95% ethylene diamine (a) and 6.25parts of 1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane (β).

These polyurethane films have a much lower melting point: with ethylenediamine, 203° C, softening considerably before melting at above 152° C,with 1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane 214° C, softeningbefore melting at above 178° C. In addition, a distinct reduction instrength on exposure to light is also observed (see Table 3).

                                      Table 3                                     __________________________________________________________________________    Example Exposure                                                                           Ultimate tensile                                                                      Breaking elongation                                                                     Modulus 300%                                   No.     Time strength g/dtex                                                                       %         mg/dtex                                        __________________________________________________________________________    3 a)    original                                                                           0.69    487       219                                                    66 hours                                                                           0.57    445       210                                                    110 hours                                                                          0.50    474       188                                                    154 hours                                                                          0.25    360       163                                            3 b/α                                                                           original                                                                           0.64    450       168                                            (ethylene                                                                     diamine)                                                                              66 hours                                                                           0.22    452        87                                                    110 hours                                                                          0.17    422        74                                                    154 hours                                                                          cannot be                                                                             --        --                                                          measured                                                         3 b/β                                                                            original                                                                           0.66    450       254                                            (1-amino-3-                                                                   aminomethyl-                                                                          66 hours                                                                           0.57    457       223                                            3,5,5-trimethyl                                                               cyclohexane)                                                                          110 hours                                                                          0.29    382       182                                                    154 hours                                                                          0.15    327       112                                            __________________________________________________________________________

EXAMPLE 4

1500 parts of an adipic acid/1,6-hexane diol/2,2-dimethyl-1,3-propanediol mixed polyester with a molecular weight of 1670 (molar ratio of theglycols 65 : 35) are heated for 4 hours to 100-110° C with 30.1 parts ofN,N-bis-(β-hydroxy propyl)-methyl amine, 425.6 parts of1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane and 485parts of toluene. Thereafter the prepolymer solution has an NCO-contentof 3.34% NCO (based on solids).

38.9 parts of 1,4-diamino cyclohexane (17.3% cis/82.7% trans) aredissolved in 1961 parts of toluene/isopropanol (1 : 1) and the resultingsolution intensively stirred with 1073 parts of prepolymer solution.After dilution of the highly viscous solution to 25%, the homogeneouselastomer solution has a viscosity 390 poises/20° C.

The films show favorable mechanical properties, a melting point of 260°C and a softening range of from about 222 to 235° C.

After the solution has been cast to form a reversal film, the followingproperties were measured on the clear, tack-free film; shore hardness86, ultimate tensile strength 600 kg/cm², breaking elongation 580%;ultimate tensile strength after 66 hours Fade-o-meter testing 290kg/cm², elongation 670%; after 400 hours Fade-o-meter testing 250kg/cm², 660% elongation. After hydrolysis for 7 days at 70° C/95%relative humidity, the films have a residual strength of 540 kg/cm² at470% elongation which, after 14 days falls to 410 kg/cm² at 620%elongation.

EXAMPLE 5

800 parts of a hexane diol polycarbonate of molecular weight 1925, 15.78parts of N,N-bis-(β-hydroxy propyl)-methyl amine, 208.8 parts of1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane and 257parts of toluene, are heated to 110-115° C until the NCO-content of theprepolymer solution has fallen to 3.365% NCO (based on solid substance).36.6 parts of 1,4-diamino cyclohexane (30% cis/70% trans) are mixed with1958 parts of toluene/isopropanol (1 : 1) and 1000 parts of the aboveNCO-prepolymer solution, resulting in the formation of a homogeneous,storage-stable clear elastomer solution. The film begins to softenfairly considerably at around 220° C and becomes liquid above 260° C.The film properties are shown in Table 4.

Testing of the mechanical properties of films which can be furtherprocessed by the reversal process gives the following data (accompaniedfor comparison by the data of a comparison substance of similarcomposition extended with 1-amino-3-amino methyl-3,5,5-trimethylcyclohexane):

    ______________________________________                                                                  Comparison                                                     Example 5      test                                                ______________________________________                                        micro hardness                                                                              82               84                                             ultimate tensile                                                              strength kg/cm.sup.2                                                                       570              480                                             breaking elongation %                                                                      370              340                                             7 days hydrolysis at                                                          70° C/95% relative                                                                  (strength/elongation)                                            humidity     525/390          450/420                                         14 days hydrolysis                                                            under the same                                                                conditions   510/380          440/380                                         400 hours Xeno-                                                                            (strength/elongation)                                            testing      470/410          315/380                                         swelling in                                                                   perchlorethylene                                                                           26%              90%                                             ______________________________________                                    

The solutions of Example 5 give high-strength, hydrolysis-resistant andlight stable polyurethane coatings which show extremely low swellingand, hence, high dry-cleaning resistance.

EXAMPLE 6

720 parts of the hexane diol polycarbonate used in Example 1 and 80parts of an adipic acid-1,6-hexane diol/2,2-dimethyl-1,3-propane diolpolyester with the same composition as in Example 4, are heated for 160minutes to between 95 and 98° C with 194.5 parts of1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane and 57parts of dicyclohexyl methane-4,4'-diisocyanate (molar ratio of thediisocyanate 80 : 20) in 265 parts of toluene, resulting in theformation of an NCO-prepolymer with an NCO-content of 5.44% (based onthe solids content).

13.45 parts of 1,4-diamino cyclohexane (36/64 cis/trans-mixture) and4.48 parts of dicyclohexylmethane-4,4'-diamine (97.7%) [molar ratio ofthe diamines 85 : 15] are dissolved in 604 parts of toluene/isopropanol(1/1), and 259 parts of the above NCO-prepolymer solution added,resulting in the formation of a highly viscous elastomer solution (860poises) which, after dilution to 21%, has a viscosity of 95 poises andcan be dried to form clear films.

The films have a melting point of 265° C and a softening point of from235 to 240° C. Highly flexible finishes resistant to flexing andunaffected by hydrolysis are obtained from the solution.

If the above NCO-prepolymer solution is chain-extended withcorresponding quantities of ethylene diamine or 1-amino-3-amino methyl-3,5,5-trimethyl cyclohexane, much lower-melting films are obtained.

If it is attempted to synthesize an NCO-prepolymer solution from amixture of 50/50 mol % of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane/dicyclohexyl methane diisocyanate,and if the solution in toluene/isopropanol is chain-extended as abovewith 1,4-diamino cyclohexane, an unstable solution is obtained whichvery quickly turns into a plaste and can no longer be spread.

                                      TABLE 4                                     __________________________________________________________________________    Soluton and film properties of the polyurethane ureas according to            Examples 3 to 6                                                               ("softer" coating type -- approximately 3.5% of NCO in the prepolymer)               1,4-diamino                                                                   cyclohexane cis/                                                                           solution viscosity                                                                          solution                                    Example                                                                              trans content                                                                              poises/20° C                                                                         concentration                                                                            η.sub.i -value               __________________________________________________________________________    3 a)   17.3/82.7    266           26.2       0.70                             3 b)   comparison tests                                                              with ethylene                                                                 diamine       90           26.2       --                                      1-amino-3-amino                                                                            165           26.2       --                                      methyl-3,5,5-                                                                 trimethyl cyclohexane                                                  4      36/64        390           25         --                               5      30/70        260           28         0.81                             6      36/64        860           25         --                                               HDT determined                                                                          melting behavior                                    Ultimate  Breaking                                                                            in accordance with                                                                      Kofler bench                                             tensile                                                                            elongation                                                                          DOS 1.700.591                                                                           softening                                                                           melting point                                 Example                                                                            g/dtex                                                                             %     ° C                                                                              ° C                                                                          (liquid) ° C                                                                  solvent                                __________________________________________________________________________    3 a) 0.69 487   150       >(225 -235)                                                                         260    Solvesso-100/ethylene                                                         glycol (1:1)                           3 b) 0.64 450    69       from 152                                                                            203    Solvesso-100/ethylene                                                         glycol (1:1)                                0.66 450   106       from 178                                                                            214    Solvesso-100/ethylene                                                         glycol (1:1)                           4    0.74 525   118       >222-235                                                                            260    toluene/isopropanol                    5    0.82 436   117       >220  260    toluene/isopropanol                    6    0.68 464   154       >240  >260   toluene/isopropanol                                                           (prepolymer: 5.44%                                                            NCO finish type)                       __________________________________________________________________________

EXAMPLE 7 NCO-prepolymer formation

1300 parts of the hexane diol polycarbonate described in Example 1 and145 parts of the mixed polyester of Example 4 are reacted at around 980°C with 339 parts of 1-isocyanato-3-isocyanato methyl-3,5,5-trimethylcyclohexane and 446 parts of toluene to form an NCO-prepolymer with anNCO-content of 3.60% (based on solid substance).

Reaction with diamino cyclohexane in perchlorethylene/isopropanol assolvent

8.48 parts of diamino cyclohexane (36/64 cis/trans) are dissolved in a 1: 1 mixture of perchlorethylene and isopropanol (570 parts) and theresulting solution stirred with 205 parts of the above prepolymersolution until the viscosity of the approximately 22% solution has risento 340 poises. The excess terminal amino groups are removed by theaddition of approximately 0.7 parts of butyl isocyanate.

Reaction in trichlorethylene/isopropanol as solvent

4.24 parts of diamino cyclohexane (34/64cis/trans) are dissolved in 207parts of trichlorethylene and 89 parts of isopropanol and the resultingsolution stirred with 107.5 parts of the above NCO-prepolymer solutionto form a homogeneous, clear solution with a viscosity of 293 poises: c= 22%.

Clear, highly elastic films are obtained from the elastomer solutions,giving a soft tack-free feel after lamination on to cotton fabric. Thecoatings are extremely resistant to hydrolysis.

It is to be understood that any of the components and conditionsmentioned as suitable herein can be substituted for its counterpart inthe foregoing examples and that although the invention has beendescribed in considerable detail in the foregoing, such detail is solelyfor the purpose of illustration. Variations can be made in the inventionby those skilled in the art without departing from the spirit and scopeof the invention except as is set forth in the claims.

What is claimed is:
 1. A polyurethane polyurea prepared by a processwhich comprises, reacting in an inert organic solvent aa. chain extendercomprising at least 80 mol % 1,4-diamino cyclohexane with acis/trans-isomer ratio of from 10/90 to 60/40, with b. an isocyanatoterminated prepolymer prepared by a process which comprises reactingi.substantially linear polyhydroxyl compounds with molecular weights offrom 500 to 5000, with ii. aliphatic or cycloaliphatic diisocyanates,.Iadd.wherein such diisocyanates consist of at least 75 mol % of1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane, the.Iaddend.molar ratio of hydroxyl groups to isocyanate groups beingbetween about 1 : 1.5 and 1 : 5,and evaporating the solvent.
 2. Theproduct of claim 1 wherein the solvent used is a mixture of an aromatichydrocarbon, or chlorinated aliphatic hydrocarbon, with primarysecondary or tertiary aliphatic alcohols.
 3. A product according toclaim 1 wherein the isocyanato terminated prepolymers are prepared fromsubstantially linear polyhydroxyl compounds with molecular weights offrom about 62 to
 400. 4. The product of claim 1 wherein the prepolymers,diamines and chain extenders are reacted in a solvent mixture ofchlorinated aromatic hydrocarbons.
 5. The product of claim 1 wherein thepolyhydroxyl compounds are dihydroxy polyesters, polycarbonates orpolyacetones.
 6. The product of claim 1 wherein the prepolymer includesdiols with a tertiary amino group. .[.7. The product of claim 1 whereinthe diisocyanate mixture contains at least 75 mol % of1-isocyanato-3-isocyanato methyl-3,5,5-trimethyl cyclohexane..].
 8. Theproduct of claim 1 wherein the molar ratio of isocyanate groups to aminegroups in the chain extending reaction is between 1 : 1.0 and 1 : 1.15.The product of claim 1 wherein polyhydroxyl compound has a molecularweight of from 800 to 3000 and a melting point below 45° C by the KoflerBench method.
 10. The product of claim 1 wherein the prepolymer includesa dihydroxy polyester selected from the group adipic acid-ethyleneglycol, -1,6-hexane diol, -2,2-dimethyl propane diol, -1,4-butane diolor -1,2-propane diol.